From the past, some methods have been proposed for displaying a stereoscopic image on a display screen of a PC (Personal Computer) and the like. In the methods, a method has been proposed for displaying a three-dimensional stereoscopic image of a display object by overlapping a plurality of two-dimensional images (refer to following patent documents 1 and 2).
The display method described in the patent documents 1 and 2 is called a DFD (Depth-Fuse 3D) display scheme. In the three-dimensional display method of the DFD display scheme, an image having a three-dimensional appearance in the depth direction can be displayed by changing brightness of a display object on each plane of the plurality of two-dimensional images to be overlapped (in the case of brightness distribution type DFD display), or by changing transparency (in the case of transparency distribution type DFD display).
According to the display method of the DFD display scheme, since resolution of the display object is the same as the resolution of a normal two-dimensional image, the scheme has a characteristic that even a small display object such as a small character can be clearly displayed with high resolution.
There are following documents as prior art documents relating to the present invention.    [Patent document 1] Japanese Patent No. 3022558    [Patent document 2] Japanese Patent No. 3460671